Surgical anchor and method for using the same

ABSTRACT

An anchor for attaching an object within a tunnel extending through a workpiece such as a bone or a bone-like structure, and a method for using the same. The anchor includes a body and a plurality of barbs located in circumferentially spaced relation about the body. The barbs are formed of a material which may be elastically deformed from a normal configuration wherein the outer ends of the barbs extend radially outwardly of the body toward a configuration wherein the barbs are located generally parallel to the longitudinal axis of the body. A diametrical opening in the front portion of the anchor is provided for engagement by a length of cord-like material such that the anchor may be pulled into a bone tunnel, and an opening in the rear portion of the anchor is provided for attaching either a ligament, tendon or the like to the anchor, or for grasping a bone plug or similar rigid object attached to a free end of the ligament, tendon or the like.

This is a division of U.S. application Ser. No. 08/075,168, filed Jun.10, 1993, now U.S. Pat. No. 5,505,735 Apr. 09, 1996 for Surgical AnchorAnd Method For Using The Same.

FIELD OF THE INVENTION

The present invention relates generally to fastening devices. Moreparticularly, the invention relates to devices for attaching portions ofobjects within tunnels formed in bones or bone-like structures, and tomethods for using the same.

BACKGROUND OF THE INVENTION

The complete, or partial, detachment of ligaments, tendons or other softtissues from their associated bones within the body is a relativelycommonplace injury, particularly among athletes. Such injuries generallyresult from excessive stresses being placed on these soft tissues. Forexample, a tissue-detaching injury may occur as the result of anaccident such as a fall, overexertion during a work-related activity,during the course of an athletic event, or in any one of many othersituations and/or activities.

In the case of a partial detachment, commonly referred to under thegeneral term "sprain", the injury will frequently heal itself, if givensufficient time, and if care is taken not to expose the injury to anyundue or extraordinary stress during the healing process. If, however,the ligament or tendon is completely detached from its associated boneor bones, or if it is severed as the result of a traumatic injury,partial or permanent disability may result. Fortunately, a number ofsurgical techniques exist for re-attaching such detached tissues and/orcompletely replacing severely damaged tissues.

One such technique involves the re-attachment of the detached tissueusing "traditional" attachment devices such as metal staples, suturesover buttons and cancellous bone screws. Such "traditional" attachmentdevices have also been used to attach tendon or ligament substitutes(often formed of autogenous tissue harvested from elsewhere in the body)to the desired bone or bones.

Another technique is described in detail in U.S. Pat. No. 4,950,270entitled "Cannulated Self-Tapping Bone Screw" issued Aug. 21, 1990 toBowman et al. This patent is specifically incorporated herein byreference. In this technique, an anterior cruciate ligament in a humanknee, for example, is replaced and/or repaired by forming bone tunnelsthrough the tibia and/or femur at the points of normal attachment of theanterior cruciate ligament. A ligament graft, with a bone block (orplug) on at least one of its ends, is sized to fit within the bonetunnels. Suture is then attached to the outer end of each bone plug, andthereafter passed through the femoral and/or tibial bone tunnels. Thefemoral plug and/or the tibial plug is/are then inserted into theappropriate bone tunnel behind the suture. Subsequently, the suture isdrawn tight (simultaneously in opposite directions, in cases where boneblocks are to be located in both a femoral bone tunnel and a tibial bonetunnel). This procedure positions the bone plug (or plugs) in thedesired location, and imparts the desired degree of tension to theligament or ligament substitute. Finally, while holding the bone blocksin position, a bone screw is inserted between each bone block and theside wall of its associated bone tunnel so as to securely lock the boneblock in position using a tight interference fit.

Alternatives to the foregoing use of bone screws are also well known inthe art. For example, in U.S. Pat. No. 5,147,362 entitled "EndostealLigament Fixation Device", issued Sep. 15, 1992 to E. Marlowe Goble,rearwardly extending flexible barbs or pins are attached to a bone plug(either directly or by a collar, cap or similar intervening element) foranchoring a bone plug within a bone tunnel. The disclosure of theforegoing U.S. Pat. No. 5,147,362 is specifically incorporated herein byreference.

In U.S. Pat. No. 4,997,433 entitled "Endosteal Fixation Stud andSystem", issued Mar. 5, 1991 to E. Marlowe Goble et al., a stud isdisclosed for attachment to the outer end of the bone block. This studincludes a pair of spaced, forwardly projecting, flexible arms. One ofthese arms includes a substantially rigid, radially and rearwardlyprojecting portion disposed adjacent the arm's outer end. The stud isinserted through a bone tunnel ahead of a bone block to which it hasbeen attached so that the projection may engage the outer surface of thebone adjacent the far end of the bone tunnel. This projection then actsto hold the bone block within the bone tunnel so long as rearwardlydirected tension is maintained on the bone block. The disclosure of U.S.Pat. No. 4,997,433 is also specifically incorporated herein byreference.

Unfortunately, the repair devices and methods described above have notbeen uniformly successful. For example, tissue re-attachments effectedusing the aforementioned "traditional" fastening devices often cannot bemaintained under even normal tensile loans.

Also, the use of sharp screws to create a locking interference fitbetween a bone plug and the side Wall of a bone tunnel introduces anumber of problems. For one thing, there is always the possibility ofdamaging the ligament or repair material during insertion of the sharpscrew. In addition, it can be difficult to maintain the desired tensionon the ligament or repair material during insertion of the screw.Furthermore, the insertion of a bone screw requires that a twistingmotion to be imparted to the screw. This twisting motion of the screwcan in turn cause rotation of the bone block within the bone tunnel. Ifthis occurs, undesirable twisting of the ligament may also occur.

The removal of such bone screws can also cause problems. In those casesin which the screw can be removed simply by unscrewing it in the usualmanner, an undesirable hole is left in the bone. In many cases, however,the screw cannot simply be unscrewed from the bone to remove it. Inthese situations, the screw must typically be either forceably pulledout of the bone, or it must be removed by chipping away the surroundingbone. Both of these removal procedures can cause serious damage to thebone.

The foregoing attachment devices of U.S. Pat. Nos. 5,147,362 and4,997,433 are also not totally satisfactory. This is because in thedevice of U.S. Pat. No. 5,147,362, the cross-sectional size of the bonetunnel must significantly exceed the cross-sectional size of the boneblock due to the particular constructions utilized. This results in thebone block being spaced from the side wall of the bone tunnel, which canin turn delay assimilation of the bone block into the bone duringhealing. The device of U.S. Pat. No. 4,997,433, on the other hand, islimited to use in a particular method of re-attachment. Furthermore,undesirable binding may occur between the stud's projection and the sidewall of the bone tunnel as the stud is forced through the bone tunnel.

Various types of suture anchors and anchors for attaching objects tobone are also well known in the art. A number of these devices aredescribed in detail in U.S. Pat. Nos. 4,898,156; 4,899,743; 4,946,468;4,968,315; 5,002,550; 5,046,513; and 5,192,303 (each of which ispresently owned by Mitek Surgical Products, Inc. of Norwood, Mass., theassignee of this application). The disclosures of these patents are alsospecifically incorporated herein by reference.

OBJECTS OF THE INVENTION

Accordingly, one object of the present invention is to provide asurgical anchor useful in the repair and/or replacement of ligaments,tendons and similar elongated soft tissues.

Another object of the present invention is to provide a surgical anchorfor holding a bone block in place in a bone tunnel, so that a piece ofsoft tissue attached to the bone block can be connected to a bone undertension.

Another object of the present invention is to provide a surgical anchorwhich avoids the danger of severing, twisting or otherwise damaging softtissue repair or replacement material.

Another object of the present invention is to provide a surgical anchorwhich may be inserted into a tunnel formed in bone without causingserious damage to the surrounding bone.

Yet another object of the present invention is to provide a surgicalanchor which is adapted to hold repair or replacement material inproximity to bone in a manner which promotes the growth of a permanentattachment therebetween.

And another object of the present invention is to provide a surgicalanchor which may be drawn, rather than pushed, into a tunnel formed inbone.

Yet another object of the present invention is to provide a surgicalanchor which includes simple and convenient means for attaching repairor replacement material or an object thereto.

And another object of the present invention is to provide an improvedmethod for repairing and/or replacing ligaments, tendons or similartissue by affixing an end of such tissue (or its replacement) within atunnel extending through a bone or bone-like structure.

SUMMARY OF THE INVENTION

These and other objects are achieved by the use of the presentinvention, which comprises a novel surgical anchor and the use of thesame. The novel surgical anchor generally comprises a body and aplurality of barbs.

The body comprises a longitudinal, axis, a front end, a rear end, afront portion adjacent the front end, a rear portion adjacent the rearend, and an outer surface. Connection means are associated with thefront portion of the body for connecting the body to anchor pullingmeans. Attachment means are associated with the rear portion of the bodyfor attaching a desired repair material (i.e., a piece of detachedtissue, a replacement for detached tissue, a bone block, or some otherobject) to the body.

The connection means preferably comprises a bore extending transverselythrough the front portion of the body, and the anchor pulling meanspreferably comprises a length of strong suture, braided twine, wire orthe like.

The attachment means may take any one of several forms. The specificform chosen will depend upon the nature of the repair material which isto be attached to the body, and upon the particular geometricalconfiguration chosen for the body itself. Accordingly, the attachmentmeans may comprise an opening extending through the rear portion of thebody. Alternatively, the attachment means may comprise a longitudinalslot extending into the rear end of the body.

In the latter slot alternative, the sections of the rear portion of thebody forming the opposing sides of the slot may be pivotally attached tothe front portion. In that case, the rear portion of the body may beopened to receive a bone block and then closed again so as tocompressively retain the bone block in engagement with the anchor as theanchor is pulled into a bone tunnel. To help facilitate the blockretention by the anchor, tines may be provided on the opposing sidewalls of the slot so as to bite into the bone block when the rearportion of the anchor is in its closed position.

In one particular embodiment of this alternative, the front portion ofthe body is formed in two pants which interlock in hinged,tongue-in-groove relation. Specifically, the tongue-defining partcarries a first section of the anchor's rear portion which defines oneof the opposing side walls of the slot. The groove-defining part carriesa second section of the anchor's rear portion which defines the other ofthe opposing side walls of the slot. The hinge is elongated hollow pinfrictionally engaging a transverse bore extending through the unitedtongue-defining and groove-defining parts. The lumen defined by thehollow pin constitutes the anchor's aforementioned connecting means.

The barbs are located in spaced circumferential relation to each otherabout the outer surface of the anchor's body. In the preferredembodiments, a plurality of identical longitudinal channels are locatedin substantially equally spaced circumferential relation to each otherabout the outer surface of the body. Each of these channels has aforward end located the same axial distance from the front end of thebody. A barb extends outwardly and rearwardly from the forward end ofeach longitudinal channel to an outer end. The outer ends of the barbsare normally located radially outwardly of an axial projection of themaximum geometrical cross-section of the body, as taken perpendicular toits longitudinal axis. In addition, each barb is capable of beingelastically deformed so that its outer end lies within theaforementioned axial projection of the maximum geometrical cross-sectionof the body. As a result of this construction, when the anchor is pulledinto an appropriately sized bone tunnel using the aforementioned anchorpulling means, the anchor's barbs will engage the side wall of the bonetunnel and be deflected inwardly so as to allow the anchor to pass downthe bone tunnel. At the same time, however, the anchor's barbs willprevent the anchor from being withdrawn from the bone tunnel in thedirection of its entry.

In the method of the invention, a length of suture-like material isthreaded through the transverse bore of the connection means, and therepair material is attached to the attachment means at the rear portionof the anchor body. In the case where the repair material constitutessoft tissue such as a ligament, tendon or the like, the connecting meansmay be in the form of a transverse opening extending through the anchorbody, and the soft repair material may be attached directly to theanchor body by looping it through the transverse opening, or byattaching it to the opening via an intervening piece of suture or thelike. In the case where the repair material constitutes a rigid elementsuch as a bone plug block disposed at a free end of a ligament, tendonor the like, the connecting means may be in the form of a transverseopening and the repair material may be attached to the anchor body viaan intervening piece of suture. Alternatively, in the case where therepair material constitutes a rigid element such as a bone blockdisposed at the free end of a ligament, tendon or the like, theconnecting means may be in the form of a slot in the rear end of thebody, and the rigid repair material may be positioned in the slot.

In any case, once the repair material has been attached to the anchorbody, the free ends of the suture-like material extending through theconnection means are inserted through a bone tunnel which is to receivethe repair material. Thereafter, the anchor is pulled into and thenalong the bone tunnel by pulling on the free ends of the suture-likematerial. As this occurs, the anchor's barbs will yieldably engage thesurrounding bone so as to permit the anchor, and hence the repairmaterial, to be pulled along the bone tunnel until it reaches a desiredposition. At the same time, however, the anchor's barbs will prevent theanchor from being withdrawn from the bone tunnel in the direction fromwhich it entered. In this way the repair material may be securelyattached to the bone using the novel surgical anchor of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention will bemore fully disclosed or rendered obvious by the following detaileddescription of the preferred embodiments of the invention, which is tobe considered together with the accompanying drawings wherein likenumbers refer to like parts, and further wherein:

FIG. 1 is a side view in partial section showing a portion of a humanfemur bone and a portion of a human tibia bone adjacent a knee joint,each having a bone tunnel extending therethrough, and showing a firstembodiment of a surgical anchor formed in accordance with the presentinvention, wherein the surgical anchor is attached directly to one endof a ligament;

FIG. 2 is a side view of the surgical anchor shown in FIG. 1;

FIG. 3 is a side view of the surgical anchor shown in FIG. 2, whereinthe anchor has been rotated 90° about its longitudinal axis;

FIG. 4 is a rear view of the surgical anchor shown in FIG. 3;

FIG. 5 is a side view similar to that of FIG. 1, but showing a secondembodiment of a surgical anchor formed in accordance with the presentinvention, wherein the surgical anchor is attached to a bone blocklocated at one end of a ligament;

FIG. 6 is a side view of the surgical anchor shown in FIG. 5, with theanchor being shown in its closed position;

FIG. 7 is a side view of the surgical anchor of FIGS. 5 and 6, with thesurgical anchor being shown in its open position;

FIG. 8 is a rear view of the surgical anchor shown in FIG. 6; and

FIG. 9 is an exploded perspective view of the components forming thesurgical anchor shown in FIGS. 5-8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 1, there is shown a portion of a human tibia 2 anda portion of a human femur 4 at the point at which they meet to form ahuman knee joint, generally indicated at 6. The knee joint 6 isstabilized by a number of ligaments (not shown in the drawings forpurposes of clarity) such as the patellar tendon, the quadriceps femuristendon, the lateral and medial collateral ligaments, and the anteriorand posterior cruciate ligaments. An anterior cruciate ligament graft 8is shown extending through a tibial bone tunnel 10 and into a femuralbone tunnel 11. A surgical anchor 12, constituting a first embodiment ofthe present invention, is shown connecting ligament 8 to femur 4.Surgical anchor 12 is attached directly to the end 13 of ligament 8which is located within femoral bone tunnel 11.

Referring next to FIGS. 2-4, surgical anchor 12 comprises a body 14having a longitudinal axis 15, a front end 16, a front portion 18adjacent front end 16, a rear end 20, and a rear portion 22 adjacentrear end 20. The outer surface 24 of front portion 18 tapers graduallytoward longitudinal axis 15 as it approaches front end 16. This providesbody 14 with a generally forwardly pointed configuration. Rear portion22 includes an outer surface 25. Body 14 is preferably formed out of6AL-4V ELI titanium. It may, however, be formed out of any suitablebiocompatible metal, biocompatible polymer or bioabsorbable material,all without departure from the present invention.

A bore 26 extends through front portion 18, perpendicular tolongitudinal axis 15. Bore 26 is sized such that a strong suture 28(FIG. 1), or some other suitable anchor pulling means, may be connectedthereto for pulling anchor 12 in a forward axial direction. In addition,tapered grooves 27 extend forwardly from the openings of bore 26 ontoouter surface 24. Grooves 27, combined with the rounding of the outeredges of bore 26, provide a smooth, substantially continuous surfaceagainst which the anchor pulling means 28 may bear. This reduces thechance of breaking the anchor pulling means 28 during deployment of theanchor.

The anchor's rear portion 22 includes an opening 30 extendingtransversely through body 14 adjacent its rear end 20. Opening 30 ispreferably, but not necessarily, oriented substantially parallel to bore26 in front portion 18. Opening 30 is sized to receive a loop ofligament, tendon or the like (FIG. 1), or a loop of suture which is inturn attached to a ligament, tendon or the like, or a loop of suturewhich is in turn attached to a bone block or plug, so as to attach thedesired repair material to the anchor, as will hereinafter be discussedin further detail. Channels 31 extend rearwardly from the openings ofaperture 30 onto outer surface 25. Channels 31 extend all the way to theanchor's rear end 20. These channels 31, combined with the rounding ofthe outer edges of opening 30, provide a smooth, substantiallycontinuous bearing surface for the tissue, tissue substitute or suturematerial looped through opening 30. This reduces the chance of breakingor otherwise damaging the looped tissue, tissue substitute or suturematerial during anchor deployment. Furthermore, if desired, the rearsection 32 of rear portion 22 which contains opening 30 may be flattenedsomewhat relative to the remainder of rear portion 22. This provides, incombination with channels 31, pathways for the looped tissue, tissuesubstitute or suture material passing through opening 30. Specifically,these pathways allow the looped material to extend along the flattenedsides of rear section 32 without danger of the looped material beingcrushed between the anchor and the adjacent side wall of the bonetunnel.

The forward section 33 of rear portion 22 includes a plurality ofequally circumferentially spaced longitudinal channels 34. Each channel34 terminates in a forward end 35 located substantially the same axialdistance from front end 16.

A plurality of barbs 36 extend outwardly and rearwardly from body 14, inspaced circumferential relation to each other. In the embodiment shownin FIGS. 1-4, one such barb 36 extends outwardly and rearwardly from theforward end 35 of each channel 34. Each barb 36 terminates in an outerend 38. Each outer end 38 is normally located radially outside theperiphery of an axial projection of the maximum geometric cross-sectionof body 14, as taken perpendicular to longitudinal axis 15. At the sametime, however, barbs 36 are formed out of an elastically deformablematerial such that outer ends 38 can be forced radially inwardly so asto be located within the periphery of an axial projection of the maximumgeometric cross-section of body 14. On account of this construction,when an anchor 12 is inserted longitudinally into an appropriately sizedbone tunnel, the outer ends 38 of barbs 36 will engage, and be deflectedinwardly by, the side wall of the bone tunnel. This yieldable engagementof barbs 36 with the adjacent bone permits the anchor to be moved alongthe bone tunnel and then fixed securely in position, as will hereinafterbe described in further detail.

In the preferred embodiment, barbs 36 are formed out of a pseudoelasticshape memory alloy of the type disclosed in U.S. Pat. No. 4,665,906entitled "Medical Devices Incorporating SIM Alloy Elements", issued May19, 1987 to Jervis, which patent is specifically incorporated herein byreference. By way of example, one such pseudoelastic shape memory alloymight be a nickel titanium alloy such as Nitinol, which is availablefrom Flexmedics of Minneapolis, Minn., among others. The use of such amaterial, in combination with the normal orientation of the barbsrelative to the anchor body, permits the barbs to initially deflectinwardly to the extent required to permit the anchor to move forward inthe bone tunnel, yet still resiliently "spring back" toward theirnormal, outwardly projecting position so as to prevent the anchor fromwithdrawing back out the bone tunnel.

In the preferred embodiment, barbs 36 are formed as curved arcsextending outwardly from body 14 when in their normal, unstressedcondition. Each barb forms an arc of approximately 90 degrees, with thelength of the barbs being selected so that when one end is inserted intoa longitudinal bore 40 extending forwardly from the forward end 35 of aslot 34, the other end extends the desired distance outwardly from body14. In this respect it will also be appreciated that the forced fit ofthe curved barb within the straight bore 40, combined with the elasticmemory of the barb, tends to hold the barb in place within the bore. Atthe same time, the sides of the associated channels 34 act to preventthe barb from twisting within the bore. The body of the anchor may alsobe crimped adjacent the bores 40 so as to further assure the lockingengagement of the barbs to body 14, if desired. It is to be appreciatedthat the lengths (and widths) of barbs 36 and longitudinal channels 34are carefully sized relative to one another, such that barbs 36 may befully received in longitudinal channels 34 to the extent necessary whenthe barbs are deformed during anchor deployment.

An axial depression 41 is provided in rear end 20 of body 14. Depression41 facilitates engagement of a thin push rod or similar device (notshown) with the anchor's rear end 20 in the event that it is desired topush the anchor into a bone tunnel. This application of a pushing forceto the rear end of the anchor may be accomplished either in conjunctionwith, or as a substitute for, a pulling force applied to the frontportion of the anchor via bore 26 and anchor pulling means 28.

Selected exemplary dimensions of two sizes (designated "A" and "B"respectively) of the surgical anchor shown in FIGS. 1-4 are set forthbelow for purposes of illustration:

    ______________________________________                                                       "A"              "B"                                           ______________________________________                                        Maximum diameter                                                                             0.315  inches    0.236                                                                              inches                                   Length         1.50   inches    0.750                                                                              inches                                   Diameter of bore 26                                                                          0.093  inches    0.075                                                                              inches                                   Length of slot 30                                                                            0.268  inches    0.195                                                                              inches                                   Width of slot 30                                                                             0.182  inches    0.146                                                                              inches                                   Angle of taper of                                                                            60     degrees   60   degrees                                  front portion 18                                                              Length of      0.193  inches    0.193                                                                              inches                                   channels 34                                                                   Width of       0.033  inches    0.033                                                                              inches                                   channels 34                                                                   Depth of       0.043  inches    0.043                                                                              inches                                   channels 34                                                                   Diameter of    0.030  inches    0.030                                                                              inches                                   barbs 36                                                                      Length of barbs 36                                                                           0.320  inches    0.320                                                                              inches                                   in straight                                                                   configuration                                                                 Width of flattened                                                                           0.220  inches    0.160                                                                              inches                                   section 32                                                                    Depth of       0.030  inches    0.020                                                                              inches                                   channels 31                                                                   Number of barbs                                                                              12               8                                             Depth of       0.040  inches    0.030                                                                              inches                                   depression 41                                                                 ______________________________________                                    

The use of surgical anchor 12 will now be described in the context ofanchoring one end of an anterior cruciate ligament 8 (or itsreplacement) to a femur 4, as shown in FIG. 1.

A length of strong suture 28 is first threaded through bore 26 in thefront portion of anchor 12. If desired, the free ends of the length ofsuture 28 may be secured together so as to facilitate grasping the freesuture ends and applying a pulling force thereto. One end of theligament or replacement material 8 is passed through opening 30 in therear portion of the anchor and tied to itself so as to form a closedloop extending through opening 30 in the anchor. Alternatively, a lengthof suture may be looped through opening 30 and then connected to theligament or replacement material 8 so as to connect the ligament orreplacement material to the anchor. Or a bone block, affixed to the end13 of a ligament or other elongate repair material 8, may be secured toopening 30 with a loop of suture.

Then suture 28, which is attached to the front end of anchor 12, isthreaded through the tibial and femoral bone tunnels 10 and 11,respectively. Bone tunnels 10 and 11 are sized so as to be just slightlylarger than the maximum diameter of anchor body 14, whereby the anchor'sbarbs 36 may engage the side walls of bone tunnels 10 and 11 as theanchor is pulled through the bone tunnels. Next, the free ends of suture28 are pulled so as to draw anchor 12 (and its associated ligament orrepair material 8) through tibial bone tunnel 10 and part way throughfemoral bone tunnel 11, until anchor 12 sits in the relatively softcancellous region 42 of femur 4. At the same time, the free end 43 ofthe ligament or repair material 8 will extend out the end of tibial bonetunnel 10, as shown in FIG. 1. It will be understood that the generallyforwardly pointed configuration of anchor 12 will facilitate its entryinto and through the bone tunnels. It will also be understood that asthe anchor is pulled along the bone tunnels, the anchor's outwardlyextending barbs 36 will engage the side walls of the bone tunnels,deflecting inwardly as required so as to allow the anchor to pass downthe bone tunnels. At the same time, however, these barbs 36 willresiliently engage the surrounding bone so as to prevent the anchor frombeing withdrawn from the bone tunnels in the direction of its entry.

Once the anchor 12 has been properly positioned in bone tunnel 11, apulling force is exerted on the opposite end 43 of ligament or repairmaterial 8 so as to firmly set barbs 36 into the cancellous region 42 offemur 4. Suture 28 may then be removed from anchor 12.

Thereafter, the other end 43 of ligament or repair material 8 may beaffixed to the tibia. This may be accomplished by using another anchor12 appropriately attached to end 43 or, alternatively, it may beattached to tibia 2 in any one of the many ways well known in the art.By way of example, if end 43 consists solely of soft tissue or tissuesubstitute, the soft tissue or tissue substitute may be attached to thetibia by staples, screws and the like. On the other hand, if end 43includes a bone block, the block can be anchored in bone tunnel 10 usingan interference screw. Such attachments are of the sort well known inthe art.

Referring next to FIG. 5, there is shown a surgical anchor 112 whichconstitutes a second embodiment of the invention. Surgical anchor 112 isin many respects similar to the aforementioned anchor 12, although it isalso different in many ways as well. More particularly, surgical anchor112 is specifically adapted to engage and grip a bone block or plug 113which is attached to one end of a ligament or other repair material 8,and to attach it to a bone. In FIG. 5, surgical anchor 112 is shownattaching bone block 113 to a femur 4.

Looking now at FIGS. 5-19, anchor 112 comprises a body 114, alongitudinal axis 115, a front end 116, a front portion 118 adjacentfront end 116, a rear end 120, and a rear portion 122 adjacent rear end120. The outer surface 124 of front portion 118 tapers gradually towardlongitudinal axis 115 as it extends toward front end 116. This taperingprovides body 114 with a generally forwardly pointed configuration. Abore 126 extends diametrically through front portion 118, perpendicularto longitudinal axis 115. Bore 126 is sized such that a strong suture 28(FIG. 5), or some other suitable anchor pulling means, may be connectedthereto for pulling anchor 112 in a forward axial direction.

Rear portion 122 includes a diametrical slot 130 located insubstantially the same plane as bore 126. Slot 130 extends forwardlyfrom rear end 120. The opposing side walls 132 and 134 defining slot 130each includes a plurality of inwardly extending tines 136. Tines 136 mayextend into slot 130 substantially perpendicular to side walls 132 and134 as shown, or tines 136 may extend at an acute angle to thelongitudinal axis of surgical anchor 112. In the preferred embodiment,each of the side walls 132 and 134 includes six tines 136 extending intoslot 130. These six barbs are arranged in three groups of two barbseach, one group adjacent each open side of the slot 130 (FIG. 9).

Rear portion 122 is formed out of two sections 138 and 140, with thesections 138 and 140 being separated by slot 130. At least one of thesections 138 and 140 is pivotally attached to front portion 118 of body114. In this way sections 138 and 140 can be moved between a closedposition in which walls 132 and 134 confront one another in parallel,opposing relation across slot 130 (FIG. 6) and an open position in whichwalls 132 and 134 are moved away from one another (FIG. 7). Thisarrangement facilitates positioning a bone block between walls 132 and134 for engagement by anchor 112. More specifically, when a bone blockis to be positioned between the side walls 132 and 134 of slot 130,sections 138 and 140 are swung away from one another so that the anchoris in its aforementioned open position, and then the bone block ispositioned between the side walls 132 and 134. Then sections 138 and 140are swung back toward one another so that the anchor is in itsaforementioned closed position, with the bone block being clampedsecurely between the anchor's opposing side wall surfaces 132 and 134.During use, the anchor will normally be maintained in its closedposition, and the bone block thereby held by the anchor, due to theengagement of the anchor with the surrounding wall of the bone tunnel,as will hereinafter be discussed in further detail. Retention of thebone block is further enhanced by virtue of the fact that tines 136 diginto the sides of the bone block and help hold it in slot 130. Inaddition, circumferential grooves 141 and 142 are provided in portions138 and 140, respectively, to permit a length of suture or othercord-like material (not shown) to be tied around rear portion 122 aftera bone block has been positioned in slot 130. This suture tie willfurther ensure that the anchor will remain in its closed position andthe bone block retained by the anchor during use.

Suture anchor 112 also comprises a plurality of longitudinal channels144 formed in anchor sections 138 and 140. Channels 144 generallycorrespond to the channels 34 discussed above with respect to surgicalanchor 12. It is to be appreciated, however, that in anchor 112 thechannels 144 are located adjacent the anchor's rear end 120, in outersurfaces 148 and 150, respectively, of sections 138 and 140. One barb151 extends outwardly and rearwardly from each of the channels 144.Barbs 151 are substantially the same as the barbs 36 discussed abovewith respect to surgical anchor 12. Bores 152 extend forwardly from theforward ends 154 of channels 144 to provide a mounting means for barbs151, in a manner similar to the way bore 40 provide a mounting means forbarbs 36 in anchor 12. It is to be appreciated that by mounting barbs151 to, body 114 adjacent rear end 120, the engagement of barbs 151 withthe surrounding bone during anchor deployment will have the effect offorcing anchor sections 138 and 140 further together, so as to ensurethat the bone block will be retained by the anchor.

The specific manner in which the anchor's rear sections 138 and 140 arehinged to one another may take several forms. All of these forms arecontemplated to fall within the scope of the present invention in itsbroadest forms. In the preferred embodiment, however, body 114 is formedin two pieces, indicated generally at 160 and 162 in FIG. 9. Piece 160includes section 138 of rear portion 122 and a center segment 164 offront portion 118, where center segment 164 extends perpendicular to theaxis of bore 126. Piece 162, on the other hand, includes section 140 ofrear portion 122 and the two side segments 166 and 168 of front section118. Side segments 166 and 168 combine with the aforementioned segment164 to form the complete front section 118.

Pieces 160 and 162 are formed so as to allow them to rotate relative toeach other about bore 126. In the embodiment shown, this is accomplishedby slightly spacing portion 170 of piece 160 from the adjacent section140, and tapering it outwardly and forwardly. At the same time, portions172 and 174 of piece 162 are slightly spaced from the adjacent section138, and also are tapered outwardly and forwardly.

Body 114 is assembled by sliding center segment 164 between sidesegments 166 and 168, in tongue-in-groove relation. In thisconfiguration, a bore 175 in center segment 164 is aligned with bores176 and 177 in side segments 168 and 166, respectively. Thereafter, ahollow pin 180 is inserted into bores 176, 175 and 177. The outersurface of pin 180 frictionally engages the walls of segments 168, 164and 166 so as to hinge pieces 160 and 162 to each other. The centrallumen of hollow pin 180 forms the aforementioned bore 126 which is toreceive anchor pulling means 28. It will be understood that the spacingand tapering of portions 170, 172 and 174 relative to the adjoiningsections 138 and 140 facilitates the pivotal movement of pieces 160 and162 relative to each other. This is because center segment 164 isallowed to pivot freely a preselected distance about pin 180.

Selected exemplary dimensions for anchor 112 are set forth below:

    ______________________________________                                        Length                 0.81   inches                                          Maximum Diameter       0.40   inches                                          Width of Slot 130 (Fig. 6)                                                                           0.170  inches                                          Length of Channels 144 0.180  inches                                          Length of Barbs 151 in their                                                                         0.28   inches                                          straight configuration                                                        Diameter of Barbs 151  0.03   inches                                          Angular spacing between                                                                              30°                                             Channels 144                                                                  Internal Diameter of Pin 180                                                                         0.08   inches                                          ______________________________________                                    

The use of surgical anchor 112 will now be described in the context ofanchoring one end of an anterior cruciate ligament 8, having a boneblock 113 attached thereto, to a femur 4, as shown in FIG. 5.

A length of strong suture 28 is first threaded through bore 126 in thefront portion of the anchor. If desired, the free ends of the length ofsuture may be secured together to facilitate grasping the free sutureends and applying a pulling force thereto. Anchor 112 is placed into itsopen position (FIG. 7) and the bone block 113 (affixed to the end of theligament or other elongate soft tissue repair material 8) is locatedbetween sections 138 and 140.

As is well known in the art, the bone block 113 and ligament 8 may be anatural tissue graft harvested from elsewhere in the patient as a singlegraft or as several different grafts, or they may be taken wholly orpartially from another donor, or they may be made up at least in part ofartificial material, depending upon the situation. The bone block alsomay be formed, cut and/or shaved into substantially any shape desired. Abox-like configuration is frequently preferred. Preferably bone block113 is sized so that it will completely fill the anchor's slot 130 andso that the sides of the bone block will just project through the opensides of the slot, whereby the bone block will substantially engage theside wall of the bone tunnel upon anchor insertion. This facilitatesassimilation of the bone block into the surrounding bone.

In any case, once bone block 113 has been located between anchorsections 138 and 140, the anchor is placed into its closed position(FIG. 6) whereby anchor surfaces 132 and 134 will grip bone block 113.Tines 136 will help hold the bone block to the anchor. A length ofsuture may then be tied into anchor grooves 141 and 142 to help hold thetwo sections of the anchor closed. Next, anchor pulling means 28 isthreaded through the tibial and femoral bone tunnels 10 and 11,respectively. Thereafter, the free ends of the suture 28 is pulled so asto draw the anchor 112 (and hence its associated bone block 113 andligament 8 as well) through tibial bone tunnel 10 and part way throughfemoral bone tunnel 11, until anchor 112 sits in the relatively softcancellous region 180 in femur 4. At the same time, the free end 182 ofligament 8 will extend out of tibial bone tunnel 10, as shown in FIG. 5.It will be understood that the generally forwardly pointed configurationof the anchor will facilitate its entry into and through the bonetunnels. It will also be understood that as the anchor is pulled alongthe bone tunnels, the outwardly extending barbs 151 will engage the sidewalls of the bone tunnels, deflecting inwardly so as to allow the anchorto pass down the bone tunnels. This engagement of barbs 151 with thewall of the bone tunnels will tend to force anchor segments 138 and 140together, thereby further ensuring that the anchor will tightly gripbone block 113 and prevent the graft from separating from the anchor.Barbs 151 will resiliently engage the surrounding bone so as to preventthe anchor from being withdrawn from the bone tunnels in the directionof its entry.

Once anchor 112 is properly positioned in bone tunnel 11, a pullingforce is exerted on the opposite end 182 of ligament or repair material8 so as to firmly set barbs 151 into the cancellous region 180 of femur4. Suture 28 may then be removed from anchor 112.

Thereafter, the other end 182 of ligament or repair material 8 may beaffixed to the tibia. This may be accomplished by using an anchor 112appropriately attached to the end 182, if end 182 includes a bone block,or by using an anchor 12, or, alternatively, it may be attached to tibia2 in any one of the many other ways well known in the art, e.g. bystaples, screws or the like, depending on the nature of graft end 182.

Numerous variations, modifications, adjustments, alterations andalternative uses of the present invention will occur to those skilled inthe art in view of the foregoing description of two exemplary andillustrative embodiments of the invention.

Thus, for example, one might use an anchor 12 or an anchor 112 in asetting other than the knee. Furthermore, one might vary the spacing andnumber of barbs 36 and/or barbs 151. Or one might form tines 136 with analternative geometry. These and other changes of their type are allconsidered to be within the scope of the present invention in itsbroadest forms.

It will, therefore, be understood that this specification is intended tobe illustrative only, and in no way limiting of the invention. The onlylimitations of the breadth and scope of this invention are set forth inthe appended claims.

ADVANTAGES OF THE INVENTION

Numerous advantages are obtained by practicing the present invention.

For one thing, a surgical anchor is provided which is useful in therepair and/or replacement of ligaments, tendons and similar elongatedsoft tissues.

Also, a surgical anchor is provided for holding a bone block in place ina bone tunnel, so that a piece of soft tissue attached to the bone blockcan be connected to a bone under tension.

And the present invention provides a surgical anchor which avoids thedanger of severing, twisting or otherwise damaging soft tissue repair orreplacement material.

Furthermore, the present invention provides a surgical anchor which maybe inserted into a tunnel formed in a bone without causing seriousdamage to the surrounding bone.

And a surgical anchor is provided which is adapted to hold repair orreplacement material in proximity to bone in a manner which promotes thegrowth of a permanent attachment therebetween.

And the present invention provides a surgical anchor which may be drawn,rather than pushed, into a tunnel formed in bone.

Furthermore, the present invention provides a surgical anchor whichincludes simple and convenient means for attaching repair or replacementmaterial or an object thereto.

And the present invention provides an improved method for repairingand/or replacing ligaments, tendons or similar tissue by affixing an endof such tissue (or its replacement) within a tunnel extending through abone or bone-like structure.

What is claimed is:
 1. A surgical anchor for fixedly locating a free endof a ligament, tendon or a similar elongated, non-rigid member formedfrom natural or artificial materials or both having a substantiallyrigid object attached to at least one free end thereof within a piece ofbone or bone-like material defining a substantially symmetrical tunneltherein, comprising:a body adapted for longitudinal insertion into saidtunnel, and a plurality of barbs; said body having a longitudinal axis,an outer surface, a front end, a rear end, a front portion adjacent saidfront end, a rear portion adjacent said rear end, connection meansassociated with said front portion, and attachment means associated withsaid rear portion, said connection means being adapted to connect saidanchor to anchor pulling means, and said attachment means being adaptedto connect said rigid object to said anchor, said attachment meanscomprising a first section of said rear portion defining a first walland a second section of said rear portion defining a second wall, saidfirst and second walls being located in facing parallel relation so asto together define a diametrical slot extending through said body fromsaid rear end to said front portion, at least one of said first and saidsecond sections being pivotally movable relative to said front portionof said body; and said barbs each comprising an outer end and an innerend, said inner end being attached to said body, and each said barbbeing formed and connected to said body so that said outer end isnormally disposed outwardly beyond an axial projection of the maximumtransverse cross-section of said body, but each said barb beingelastically deformable so that said outer end may be disposed inwardlyof an axial projection of the maximum transverse cross-section of saidbody.
 2. The surgical anchor of claim 1 wherein said first and secondwalls each define at least one inwardly facing tine extending therefromat an acute angle pointed in a direction substantially opposite to thedirection of intended forward movement of the anchor in said tunnel. 3.The surgical anchor of claim 1 wherein said front portion of said bodydefines a bore extending transversely therethrough and includes a firstpart, a second part and a hollow pin; said hollow pin being locatedwithin said bore such that said first part and said second part arepivotally movable relative to each other about said hollow pin; andwherein each of said first and second sections of said rear portion ofsaid body is attached to a separate one of said parts of said frontportion of said body.
 4. The surgical anchor of claim 1 wherein saidbarbs are formed of wire.
 5. The surgical anchor of claim 4 wherein saidwire is made of a pseudoelastic shape memory alloy.
 6. The surgicalanchor of claim 1 wherein said body defines a plurality of identicallongitudinal channels located substantially adjacent said rear end ofsaid body, said channels being located in circumferentially spacedrelation to each other about said outer surface, each said channelincluding a forward end lying in the same plane transverse to saidlongitudinal axis; andone of said plurality of barbs extends outwardlyand rearwardly from a forward end of each of said channels.
 7. Thesurgical anchor of claim 6 wherein three of said longitudinal channelsare located adjacent said rear end on the outer surface of the first andsecond sections of the rear portion of the body, respectively.
 8. Amethod of affixing a rigid object attached to a free end of a ligament,tendon or similar elongate, non-rigid object formed of natural orartificial material within a piece of bone or bone-like materialdefining a substantially symmetrical tunnel therein, comprising thesteps of:(a) providing a body adapted for longitudinal insertion intosaid tunnel, and a plurality of barbs; said body having a longitudinalaxis, an outer surface, a front end, a rear end, a front portionadjacent said front end, a rear portion adjacent said rear end,connection means associated with said front portion, and attachmentmeans associated with said rear portion, said connection means beingadapted to connect said anchor to anchor pulling means, and saidattachment means being adapted to connect said rigid object to saidanchor, said attachment means comprising a first section of said rearportion defining a first wall and a second section of said rear portiondefining a second wall, said first and second walls being located infacing parallel relation so as to together define a diametrical slotextending through said body from said rear end to said front portion,and at least one of said first and said second sections being pivotallymovable relative to said front portion of said body; said barbs eachcomprising an outer end and an inner end, said inner end being attachedto said body, and each said barb being formed and connected to said bodyso that said outer end is normally disposed outwardly beyond an axialprojection of the maximum transverse cross-section of said body, buteach said barb being elastically deformable so that said outer end maybe disposed inwardly of an axial projection of the maximum transversecross-section of said body; (b) connecting a length of suture orsuture-like material to said connecting means; (c) attaching said rigidobject between said first and said second walls of said attachmentmeans; (d) threading the free ends of said suture or suture-likematerial through said tunnel in said bone or bone-like material; and (e)pulling on the free ends of said suture or suture-like materialextending through said tunnel to thereby draw said anchor and the end ofsaid ligament, tendon or similar elongate non-rigid object attached tosaid rigid object into said tunnel to a desired depth.